The present invention relates generally to the field of robotics and specifically to a rapid-connect communication bus between the master and tool modules of a robotic tool coupler.
Industrial robots have become an indispensable part of modern manufacturing. Whether transferring semiconductor wafers from one process chamber to another in a cleanroom or cutting and welding steel on the floor of an automobile manufacturing plant, robots perform many manufacturing tasks tirelessly, in hostile environments, and with high precision and repeatability.
In many robotic manufacturing applications, it is cost-effective to utilize a relatively generic robot to accomplish a variety of tasks. For example, in an automotive manufacturing application, a robot may be utilized to cut, grind, or otherwise shape metal parts during one production run, and perform a variety of spot welding tasks in another. Different welding tool geometries may be advantageously mated to a particular robot to perform welding tasks at different locations or in different orientations. In these applications, a tool changer is used to mate different tools to the robot. One half of the tool changer, called the master module, is permanently affixed to a robot arm. The other half, called the tool module, is affixed to each tool that the robot may utilize. When the robot arm positions the master module adjacent the tool module connected to a desired tool, a coupler is actuated that mechanically locks the master and tool modules together, thus affixing the tool to the end of the robot arm. Utilities such as electrical current, air pressure, hydraulic fluid, cooling water, electronic or optical data signals, and the like, may be transferred through the robot changer from the master module to the tool module via mating terminals, valve connections, electrical connectors, and the like, making the utilities available to the selected tool. Tool changers and their constituent couplers are well known in the robotics arts, and are commercially available, such as from the assignee, ATI Industrial Automation of Apex, N.C.
In sophisticated robotic environments, one or more central controllers monitor and control some or all aspects of the robots' operations. To perform these monitoring and control functions, the controllers are typically connected to a robotic system communications network. One example of such a network is the DeviceNet specification promulgated by the Open DeviceNet Vendor Association (ODVA), information on which is available from odva.org. Alternatively, other network and/or point-to-point data communications system known in the art may be used. A typical robotic system communications network, such as DeviceNet, defines a plurality of nodes having specified functionality and capability, a physical connection and data communication specification, and a set of logical and operational protocols to effect orderly operation of the network and data communications between and among its nodes.
Particularly in applications where a variety of tools are utilized by a given robot in succession during an operation or sequence of operations, bringing each tool “on-line” quickly is of paramount concern. In this context, bringing a “new,” i.e., newly attached, tool “on-line” may comprise identifying the tool by reading a unique tool ID and/or tool function or class code; initializing the tool by providing configuration and/or calibration data, instructions, or the like; monitoring various parameters associated with the tool, such as the state of various safety interlock switches; and similar functions. One or more of these or other initialization functions are typically required prior to the tool being used to perform its task.
Typically, to accomplish this communication between the tool and the central controller or other nodes on the robotic system communications network, a network node is provided in the robotic coupler tool module that is attached to the tool. Upon attaching the tool to the robot by coupling the master module to the tool module, electrical power and other services are provided to the tool module and to the tool, and the tool module robotic system communications network node initializes and begins communicating with the network. This process may be lengthy, such as on the order of eight to ten seconds or more, which time is “idle” with respect to the robot performing useful work. Even if improvements to the network protocols and/or network node specifications reduce this start-up time, the provision of a fully functional network node on each tool module (hence, one per tool), is expensive and inefficient.